This invention relates to a tape feeding system and, more particularly, to a system for feeding a tape bearing repeating patterns printed thereon to a subsequent station, for example, a cutting machine where the tape is cut for each pattern.
Apparatus for feeding a tape from its roll at a constant speed for the purpose of printing or cutting are well known in the art. Such feeding apparatus generally use a drum rotating at a constant speed to pull the tape.
Generally, a tape is fed at a constant speed to a cutting machine operating at a constant rate where the tape is cut into sections of equal length. However, a problem arises when a tape has a series of repeating patterns printed thereon before it is fed to a cutting machine operating at a constant rate where it is cut into sections, each bearing one printed pattern. (Pattern-bearing sections are ready for use as labels, for example.) In such a case, however, constant feeding of the tape is undesirable because individual pattern-bearing sections of the tape are not exactly equal in length.
The factors which cause variations in length of individual pattern-bearing sections are: an accumulation of slight errors of the position of patterns on the tape during printing, an accumulation of expansion and/or shrinkage of the tape itself during printing, elongation of the tape resulting from high speed feeding under increased tension, the influence of humidity, the conditions under which the roll of tape is stored, slight slippage of tape and interference by the roll of tape occurring when the tape is taken out and the like. The difference between two pattern bearing sections adjoining each other or spaced apart a few sections is, of course, almost negligible or very slight; while a considerable difference is found between two sections spaced at a distance. Under these circumstances, if the tape is fed at a constant speed and cut to an equal fixed length, the actual position of cutting will accumulatively deviate from the desired cutting position just intermediate the adjacent patterns.